Ever since isocryptolepine, one of the indolo[3,2-c]quinoline-type alkaloids, was isolated from Cryptoleptis sanguinolenta (a plant used in traditional medicine against malaria), several indolo[3,2-c]quinoline compounds have been synthesized and extensively studied as potential antiplasmodial agents. See, e.g., Timari, G. et al., Synlett. 1997, 1067; Devaraj, R. et al., Bioorg. Med. Chem. Lett. 1997, 7, 369; Xiao, Z. et al., Bioorg. Med. Chem. 2001, 11, 2875-2878; Kumar, R. N. et al., Tetrahedron Lett. 2002, 43, 3327; Mulwad, V. V. et al., Indian J. Chem. Section B, 2003, 42B, 1937; and Miert, S. V. et al., J. Nat. Prod. 2005, 68, 674-677. Some indolo[3,2-c]quinoline compounds were prepared and evaluated for anticancer effects. See, e.g., Chen, Y. L. et al., Bioorg. Med. Chem. 2002, 10, 2705; Lin, Y. H. et al., Drug Dev. Res. 2006, 67, 743; and Hu, X. W. et al., Cell Biol. Toxicol. 2006, 22, 417. Indolo[3,2-c]quinoline compounds have a tetracyclic heterocycle that can intercalate into the double helix of DNA to block DNA replication or transcription, resulting in inhibition of tumor cell growth. See, e.g., Molina, A, et al., J. Org. Chem. 1996, 61, 5587.